Internal combustion engine lubricant



United States Patent I 2,931,775 INTERNAL COMBUSTION ENGINE LUBRICANTJames L. Jezl, Swarthmore, Pa., assignor to Sun Oil Company,Philadelphia, Pa., a corporation of New Jersey No Drawing. ApplicationDecember 16, 1954 a Serial No. 475,836 r 7 Claims. (Cl. 252-515 Thisinvention relates to an improved lubricant for use in a spark ignitioninternal combustion engine.

During the course of normal operation, spark ignition internalcombustion engines accumulate carbonaceous deposits in the combustionchambers thereof. Such deposits are deleterious in that they promoteengine knocking and pro-ignition tendencies thereby causing higheroctane fuel requirements. These deposits also increase engine wear andthus lessen the useful life of themgine. from decomposition of thelubricant and fuel, although inorganic materials derived from thedecomposition of various organo-metallic fuel or lubricant additivessuch as tetraethyl lead, iron carbonyl, and the like may also becontained in the deposits. In view of the deleterious effects ofcombustion chamber deposit accumulation, it is important and desirableto provide means by which such deposit accumulation may be reduced.

The carbonaceous deposits are derived largely It has now been discoveredthat the accumulation of carbonaceous deposits in the combustion chamberof a spark ignition internal combustion engine can be lessened byincorporating in the lubricant used in said engine a minor amount of amaterial selected from the group consisting of polynitrate esters ofpolyhydric alcohols, mono-nitro mono-nitrate hydrocarbon derivatives,and dinitro alkanes.

The polynitrate esters of polyhydric alcohols used according to thisinvention are preferably dinitrate esters of dihydric alcohols having 3or more carbon atoms per molecule. These preferred esters aresufliciently soluble in viscous mineral oil lubricants, and theyhave'sufiicient- 1y low volatility to be successfully used in reducingcarbonaceous combustion chamber deposit accumulation according to theinvention. The esters can contain substituent aliphatic or aromaticradicals. These radicals increase the solubility of the dinitrate estersin the lubricant; the radicals also decrease the ester volatility. It isalso within the scope of the invention to incorporate trinitrate estersin the lubricant.

Examples of specific polynitrate esters which are useful as sparkignition engine lubricant additives according to this invention are:propylene glycol dinitrate, trimethylene glycol dinitrate, 1,3-butyleneglycol dinitrate, 1,4- butylene glycol dinitrate, 2,3-butylene glycoldinitrate, 1,2-butylene glycol dinitrate, 1,5-amylene glycol dinitrate,2,4-amylene glycol dinitrate, 1,2-amylene glycol dinitrate, 1,6-hexyleneglycol dinitrate, 1,5-hexylene glycol dinitrate, 1,4-hexylene glycoldinitrate, 1,3-hexylene glycol dinitrate, 1,2-hexylene glycol dinitrate,2,4-heptylene glycol dinitrate, 3-phenyl-1,2-proylene glycol dinitrate,2,2-diethyl-l.3-propylene glycol dinitrate, 2-ethyl-1,3- hexylene glycoldinitrate, 2-ethyl-2-n-butyl-1,3-propylene glycol dinitrate, and thelike.

The mono-nitro mono-nitrate hydrocarbon derivatives employed aslubricant additives according to this invention should have at least 3carbon atoms per molecule in order that the additives be sufficientlysoluble in viscous mineral oil lubricant. Straight 9; branched chainmononitro mono-nitrates having aliphatic or aromatic substituents can beused. Examples of specific mono-nitro mono-nitrates which are suitablyused in accordance with this invention are: 2-nitro-propyl nitrate,2-nitro-1 butyl nitrate, Z-nitro-l amyl nitrate, 2-nitro-1 hexylnitrate, 2-nitro-1 heptyl nitrate, 2-methyl-2 nitro-1 butyl nitrate,2-ethyl-2-nitro-1 bgtyl nitrate, 2-methyl-2 nitro-1 propyl nitrate, andthe li e.

The dinitro alkane lubricant additives according to this invention canbe either aliphatic or cyclic dinitro ,alkanes. It is preferred thatthese additives contain at least 3 carbon atoms so that they aresuiiiciently soluble in viscous mineral oil lubricant. I Use of thehigher dinitro alkanes, i.e. those having 6 or more carbon atoms is preferred since such compounds are less volatile than the lower dinitroalkanes. Straight or branched chain aliphatic dinitro alkanes can beused. It is preferred that Y the nitro group is attached to. the samecarbon atom in both the aliphatic and cyclic dinitro additives of thisinvention since such additives are more readily prepared and aregenerally more eificacious in eifecting reduction of carbonaceousdeposit accumulation according to this invention than are dinitroalkanes having the nitro groups attached to different carbon atoms. Itis within the scope of the invention, however, to use the latter typedinitro alkanes-i.e. dinitro alkanes having the nitro groups attached todifferent carbon atoms, as viscous mineral oil lubricant additives.

Examples of specific dinitro alkanes which are suitable for useaccording to this invention are: 1,1-dinitro butane, 1,1-dinitropentane, 1,1-dinitro hexane, 1,1-dinitro heptane, 1,1-dinitro octane,1,1-dinitro nonane, 1,1-dinitro dccane, 1,1-dinitro undecane,1,1-dinitro cycloheptane, 1,1-cyclohexane, 1,1-dinitro cyclopentane,1,1-d-initro cyclooctane, 1,1-dinitro cyclononane, 1,1-dinitrocyclodecane, 1,1-dinitro-3-methyl cyclopentane, and the like.

In practicing this invention, the lubricant additive is added to theengine lubricant in minor amount suificient to substantially lessen theaccumulation of carbonaceous deposits in the engine combustion chambers.Normally the addition of about 0.05% to 5% by weight and preferablyabout 0.1% to 2% of additive to the lubricant is sufiicient to effectsubstantial deposit accumulation decreases. On occasion, however,amounts of additive outside of the above cited ranges can advantageouslybe used.

The lubricant to which the polynitrate esters of polyhydric'alcohols,mono-nitro mono-nitrate hydrocarbon derivatives, or dinitro alkanes areadded can be any of the known viscous mineral oil spark ignition enginelubricants. The lubricant may contain, in addition to the additives ofthis invention, any of various additives such as extreme pressureagents, detergent additives, and the like which are known in the art.

My invention is particularly useful when applied to spark ignitionengines which operate on fuel containing an organo-metallic anti-knockagent such as tetraethyl lead or iron carbonyl or the like. Suchorgano-metallic additives decompose in the engine combustion chambersand the decomposition products become incorporated in carbonaceousdeposits which are already on combustion chamber surfaces. Theseadditive decomposition products promote pro-ignition and are otherwisedeleterious when deposited in combustion chambers. Through practice ofmy invention, however, less of the additive decomposition productsbecome incorporated in carbonaceous combustion chamber deposits due tothe lessened accumulation of such carbonaceous deposits. Accordingly,pre-ignition and similar difficulties arising from the use oforgano-metallic additives are reduced through practice of thisinvention.

It is theorized, however, that the additives increase the rateot-combust ion-oflubricant'or lubricant residue in the engine combustionchambers thereby decreasing the accumulation of such residue. In anyevent, significant deposit accumulation decreases are obtained throughpractice of this invention. The beneficial results are evidenced,-' forexample, by decreased octane fuel requirements to avoid I claim:

1. Spark ignition internal combustion engine lubricant consistingessentially of viscous mineral oil and a compound selected from thegroup consisting of dinitrate esters-of dihydric alcohols, mono-nitromono-nitrate 'hydrocarbon derivatives, and dinitro alkanes, saidcompound having at least three carbon atoms per molecule, in minoramount sufiicient to substantially lessen the accumulation ofcarbonaceous deposits in the engine.

2. Spark ignition internal combustion engine lubricant consistingessentially of viscous mineral oil and a dinitrate ester of a dihydrioalcohol having at least three carbon atoms per molecule stantiallylessen the posits in the engine. '3. Spark ignition accumulation ofcarbonaceous deinternal combustion engine lubriknock-ing in sparkignition engines.

in minor amount sutficient to sub- ,mono-nitro mono-nitrate hydrocarbonderivative having at least three carbon atoms per molecule in minoramount sufiicient to substantially lessen the accumulation ofcarbonaceous deposits in the engine.

4. Spark ignition internal combustion engine lubricant consistingessentially of viscous mineral oil and a dinitro alkane having at leastthree carbon atoms per molecule in minor amount sufiicient tosubstantially lessen the accumulation of carbonaceous deposits in theengine.

'5. Lubricant composition according to claim 4 wherein said dinitroalkane has both nitro groups attached to the same carbon atom. v

6. Lubricant composition according to claim 4 wherein said dinitroalkane is an aliphatic dinitro alkane.

7. Lubricant composition according to claim 4 wherein said dinitroalkane is a cyclic dinitro alkane.

References Cited in the file of this patent UNITED STATES PATENTS1,800,997 Greenstreet Apr. 14, 1931 2,066,506 Woodbury Jan. 5, 193.72,378,466 Curme June 19, 1945 2,592,435 Lacomble Apr. :8, 1952 2,673,793'Brodhacker 'Mar. 30, 1954 2,785,662 Boyce Mar. 19, 11957

1. SPARK IGNITION INTERNAL COMBUSTION ENGINE LUBRICANT CONSISTINGESSENTIALLY OF VISCOUS MINERAL OIL AND A COMPOUND SELECTED FROM THEGROUP CONSISTING OF DINITRATE ESTERS OF DIHYDRIC ALCOHOLS, MONO-NITROMONO-NITRATE HYDROCARBON DERIVATIVES, AND DINITRO ALKANES, SAID COMPOUNDHAVING AT LEAST THREE CARBON ATOMS PER MOLECULE, IN MINOR AMOUNTSUFFICIENT TO SUBSTANTIALLY LESSEN THE ACCUMULATION OF CARBONACEOUSDEPOSITS IN THE ENGINE.